As I upload a video to Youtube I am free to write and include whatever links I want in the description of the video. These links are great for bringing visitors to my site, so do not forget to add them. But, if you were hoping that these links will give you a better Google ranking you are wrong. They are all no-follow links, meaning that Google can see them, but Google will not give them any value (neither positive nor negative value).
What about links from your YouTube profile?
As you might remember from the article about Pinterest and SEO all links from Pinterest pins and similar were no-follow. But, as you go to your actual Pinterest profile the link pointing back to your webpage or blog is a real do-follow link. As we go back to your YouTube profile you can see that you are free to add several links to it. This is great and it will absolutely bring visitors back to your blog and site, but opposite to Pinterest, all these links are no-follow links meaning again that they will not influence your Google ranking.
It was a time when YouTube had some follow links from channels and profile, but that time is over. YouTube is a great tool to spread the word about who you are and about your products and blog. As you get thousands of visitors it will also serve as a great portal which will lead people to your actual site, but as a SEO tool it has no direct value (even though it shows up in Google Webmaster tools as incoming links).
Ps: There is one exception to what I write about in this article because YouTube sometimes auto-generate pages/channels for blogs and on those auto-generated pages you will in fact be able to enjoy some do-follow links. Take a look at the following YouTube video made by Ileane at Basic Blog Tips for more information.